This disclosure relates to a light curtain component comprising a housing which extends essentially along a longitudinal direction, and having a plurality of optoelectronic emission or reception elements which are arranged in the housing and are oriented toward an upper side of the housing, and which are separated from one another along the longitudinal direction. The present invention furthermore relates to a light curtain comprising such a light curtain component.
Such light curtains are often also referred to as a photoelectric barrier arrangement or light curtain protection device. They are mostly used to safeguard hazardous regions. One frequent application example relates to the safeguarding of machines or industrial robots operating in an automated fashion. In the case of modern machines or industrial robots operating in an automated fashion, which move at considerable speeds, collisions generally lead to serious damage both to the machines or robots and to the workpieces being handled by them. This can lead to expensive production downtimes. The safety of people interacting with the machines or robots operating in an automated fashion also has the highest priority. For modern industrial robots and other machines with moving machine elements, the movement of which represents a risk for persons and other objects, it is therefore necessary to use protective devices to prevent a collision between the moving machine elements and a foreign object. To this end, the light curtains are usually arranged around the hazardous regions in order to virtually enclose these regions. As soon as a person breaks a photoelectric barrier generated by a light curtain, a shutdown signal is preferably generated, with which the dangerous working movement of the machine is stopped or the machine is brought into a safe state.
To this end, light curtains usually have a plurality of light curtain rails lying opposite one another, which interact with one another during operation of the light curtain. A light curtain rail usually contains a multiplicity of light emitters, preferably in the form of laser diodes and/or infrared diodes for emitting laser or infrared beams. A light curtain rail lying opposite this, which functions as a counterpart, contains a multiplicity of corresponding light receivers, with the aid of which the arrival of the laser or infrared beams can be detected. As soon as one of these laser or light beams is broken by a foreign object, the machine is thereupon switched off or put into a safe state with the aid of suitable control devices.
In order to ensure the greatest possible safety, so-called dead or blind zones, i.e. zones which are not covered by the light curtain, should absolutely be avoided. In the case of light curtains, which are usually assembled from individual rod-shaped light curtain rails to form a rectangular light curtain arrangement, this is often difficult to ensure particularly in the corners of the light curtain arrangement. The emission or reception elements are usually arranged at equal distances in the housings of the individual light curtain rails. In the corners of a light curtain arrangement where the ends of two light curtain rails meet one another at a right angle, however, there is usually an interruption or modification of the so-called pitch (the distance between two neighboring emission or reception elements), which leads to safety reductions in these regions.
The reason for the modified distance results from the fact that the light curtain rails meeting one another in the corners usually cannot be mounted close enough to one another because of the housing.
One solution to this problem consists in arranging the light curtain rails which meet one another in the corners overlapping with one another. This, however, requires the light curtain rails to be offset parallel to one another, which is usually undesirable for reasons of safety technology.
Another solution to this problem has been proposed by Turck GmbH & Co. KG (see Weber, A.: “Sicher ohne blinden Fleck” [Safe without a blind spot], in A & D, Vorsprung Automation, 5th Edition 2013, pp. 49-51). This solution is represented schematically in FIG. 6. The light curtain arrangement 100 proposed by Turck GmbH & Co. KG comprises two light curtain rails 102, 102′ arranged at a right angle to one another, each of which has a multiplicity of emission or reception elements 104, 104′. In order to keep the offset between the emission or reception elements 104, 104′ arranged in the corners as small as possible, in this solution the front ends 106, 106′ are not covered by the housing. Dead or blind zones can therefore be avoided in the corners. This solution, however, has the disadvantage that, because of the lack of housing coverage on the front sides 106, 106′, the front sides 106, 106′ of the individual light curtain rails 102, 102′ are not safeguarded against mechanical impact. Therefore, particularly when mounting the light curtain, but also during operation, undesired damage can occur relatively easily on the front sides 106, 106′ of the light curtain rails 102, 102′.